Silent chains, such as timing chains, are subjected to complex stresses which characteristically are concentrated in a particular area of each link and are frequently not constant. The variations of stress level are caused by changes in direction of load application as the chain is trained around these sprockets, even though the load itself may remain constant, by forces resulting from accelleration or decelleration, and by changes in the load applied to the chain such as the torsional load fluctuation resulting from the firing sequence of the engine in which the timing chain is installed, which fluctuation becomes more pronounced with engines having four or fewer cylinders. The stresses will often result in fatigue failure of the chain through formation of a crack or separation developing between the link hole receiving the pin and either the inside or outside flank of an individual link. These loads imposed on the chain also cause accelerated wear of the articulating portions or bearing area of the chain which may result in wear failure. Thus, the strength of the individual links and the wear life must be maintained in order for the chain to function properly.
The economics of chain design also impose a couple of criteria; that the individual links of the chain must be made as cheaply as possible and the number of components required to make an endless chain be kept to a minimum. The most economical way of producing the link parts is by stamping, which process produces acceptable parts of adequate quality provided the thickness of the material from which they are stamped is within a limited range.
It is therefore, an object of the present invention to provide a silent timing chain which possesses adequate strength and long wear life.
It is also an object of this invention to provide such a chain which is assembled from a minimum number of parts.
It is another object of this invention to provide such a timing chain which is economical to produce and assemble.
These and other objects of the present invention and many of the attendant advantages thereof, will become more readily apparent upon perusal of the following description and the accompanying drawing, wherein;